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参数资料
| 型号： | LTC3826IUH#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 26/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 32-QFN |
| 标准包装： | 73 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 585kHz |
| 占空比： | 99.4% |
| 电源电压： | 4 V ~ 36 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3826
APPLICATIONS INFORMATION
same in the most critical frequency range of the feedback
loop. The output voltage settling behavior is related to the
stability of the closed-loop system and will demonstrate
The R SENSE resistor value can be calculated by using the
maximum current sense voltage speci?cation with some
accommodation for tolerances:
the actual overall supply performance.
A second, more severe transient is caused by switching
R SENSE
80mV
5.84A
0.012
in loads with large (>1μF) supply bypass capacitors. The
( 5 ) 1 + (0.005)(50 ° C – 25 ° C) ?
( ) + ( ) 2 ( ) ( ) ?
( 300kHz ) = 332mW
dischargedbypasscapacitorsareeffectivelyputinparallel
with C OUT , causing a rapid drop in V OUT . No regulator can
alter its delivery of current quickly enough to prevent this
sudden step change in output voltage if the load switch
resistance is low and it is driven quickly. If the ratio of
C LOAD to C OUT is greater than 1:50, the switch rise time
should be controlled so that the load rise time is limited
to approximately 25 ? C LOAD . Thus a 10μF capacitor would
require a 250μs rise time, limiting the charging current
to about 200mA.
Design Example
As a design example for one channel, assume V IN = 12V
(nominal), V IN = 22V (max), V OUT = 1.8V, I MAX = 5A, and
f = 250kHz.
The inductance value is chosen ?rst based on a 30% ripple
Choosing 1% resistors: R1 = 25.5k and R2 = 32.4k yields
an output voltage of 1.816V.
The power dissipation on the top side MOSFET can be easily
estimated. Choosing a Fairchild FDS6982S dual MOSFET
results in: R DS(ON) = 0.035Ω/0.022Ω, C MILLER = 215pF. At
maximum input voltage with T(estimated) = 50°C:
1.8V 2
P MAIN =
22V
2 5A
0.035 22V 4 215pF
1 1
+
5 2.3 2.3
A short-circuit to ground will result in a folded back cur-
rent of:
current assumption. The highest value of ripple current
occurs at the maximum input voltage. Tie the PLLLPF
pin to GND, generating 250kHz operation. The minimum
I SC =
25mV
0.01
–
1 120ns ( 22V )
2 3.3 μ H
= 2.1A
I L = OUT 1 – OUT
( ) ( ) ( 0.022
)
inductance for 30% ripple current is:
V V
(f)(L) V IN
A 4.7μH inductor will produce 23% ripple current and a
3.3μH will result in 33%. The peak inductor current will
be the maximum DC value plus one half the ripple cur-
rent, or 5.84A, for the 3.3μH value. Increasing the ripple
current will also help ensure that the minimum on-time
of 230ns is not violated. The minimum on-time occurs at
maximum V IN :
with a typical value of R DS(ON) and δ = (0.005/°C)(20) = 0.1.
The resulting power dissipated in the bottom MOSFET is:
22V – 1.8V 2
P SYNC = 2.1A 1.125
22V
= 100mW
which is less than under full-load conditions.
t ON ( MIN ) =
V OUT
V IN ( MAX ) f
=
1 . 8 V
22 V ( 250 kHz )
= 327 n s
3826fc
26
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3827EG-1 | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Sync Step Down 4V to 36V Input 28-Pin SSOP |
| LTC3827EG-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3827EG-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3827EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3827EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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